将多个字符串放入ArrayList

Question

So I'm doing this:

        int len = lv.getCount();

    List<String> Cool = null;
    SparseBooleanArray checked = lv.getCheckedItemPositions();
    for (int i = 0; i < len; i++)
        if (checked.get(i)) {
            String item = String.valueOf(names.get(i));
            int start = item.lastIndexOf('=') + 1;
            int end = item.lastIndexOf('}');
            String TEST = item.substring(start, end);

            Log.d("Log", TEST);

            Cool = new ArrayList<String>();

            Cool.add(TEST);

        }


            String NEW = StringUtils.join(Cool, ',');

            Log.d("Log", NEW);

Which evey time replaces the thing in the list with whatever the next item is. How do i make it put the strings after each other.

Thanks for the help.

Answer 1

List<String> Cool = new ArrayList<String>();

create the list at the top

Cool = new ArrayList<String>();

and delete this line because it will always create a new list what you dont want

Answer 2

You're constructing a new ArrayList in every iteration of your for loop

 Log.d("Log", TEST);
 Cool = new ArrayList<String>(); // NOT HERE!!!!
 Cool.add(TEST);

construct it once, outside the loop

List<String> Cool = new ArrayList<String>(); // also Cool should be cool.

Answer 3

the reason it keeps resetting the list is because you initialized the List in a loop. Initialize it outside the loop and the algorithm will work.

Initialization:

Cool = new ArrayList();

Corrected code:

int len = lv.getCount();

List<String> Cool = new ArrayList<String>();
SparseBooleanArray checked = lv.getCheckedItemPositions();
for (int i = 0; i < len; i++)
    if (checked.get(i)) {
        String item = String.valueOf(names.get(i));
        int start = item.lastIndexOf('=') + 1;
        int end = item.lastIndexOf('}');
        String TEST = item.substring(start, end);

        Log.d("Log", TEST);

        Cool.add(TEST);

    }


        String NEW = StringUtils.join(Cool, ',');

        Log.d("Log", NEW);